This invention relates to an audiovisual signaling device and to a method of producing an audiovisual signal. More particularly, the audiovisual signaling device of this invention comprises an auditory output portion which produces an auditory output and a corresponding low voltage oscillatory signal, a converter portion which is responsive to and converts the low voltage oscillatory signal to a repetitively produced corresponding high voltage intermittent spike signal, a visual output portion, and a portion responsive to the high voltage intermittent spike signal to repetitively activate the visual output. The method of this invention comprises producing an auditory output and a corresponding low voltage oscillatory signal, converting the low voltage oscillatory signal to a corresponding high voltage intermittent spike signal, and producing a visual output responsive and corresponding to the high voltage intermittent spike signal.
Audiovisual signaling devices may be employed in a variety of applications, particularly those applications dealing with public safety. For example, warning or alarm systems such as fire alarm systems are ideally suited to include both auditory and visual signals to maximize the probability that they will attract attention in an emergency. Such systems typically employ means for producing an audio output such as a horn in electrical connection to means for producing a visual output such as a flash tube or strobe, as exemplified by co-assigned U.S. Pat. No. 4,101,880 (Haus), which employs electromechanical means for circuit interruption and flash tube circuitry charging. Timing circuits used to control the flash rate of visual signaling devices often employ switches to achieve proper flashing of a flash tube or strobe, as exemplified by U.S. Pat. No. 4,486,691 (Beggs).
However, as warning and alarm systems are often exposed to severe use, such as shock and vibration, it is advantageous for the circuitry and operating components associated with the system to be as simple and durable as possible. It would therefore be advantageous to avoid the use of electromechanical means, which are subject to wear and malfunction, to achieve switching, circuit interruption and flashing of the visual signal. It is one object of this invention to provide an audiovisual signaling device and method which advantageously avoids the use of electromechanical means of converting low to high voltage DC current, switching, and tube flashing to produce a visual signal.
The use of DC to DC converter circuitry to energize strobe and flash lamps is well known, as exemplified by U.S. Pat. Nos. 3,921,034 (Nakamura), 4,495,447 (Shigemi), 4,775,821 (Sikora), and 4,779,027 (Sikora). However, the use of DC to DC converter means typically requires the use of complex and costly circuitry. It would thus be advantageous, in terms of both circuit complexity and associated component cost, to employ less complex means of converting low to high voltage DC current in an audiovisual signaling device. It is another object of this invention to generate a visual signal by converting a low voltage signal to a high voltage spike signal by advantageously employing converter means which are less cumbersome and require less components than conventional DC to DC converter means.
An audiovisual signaling device may employ an oscillatory signal to generate the audio and visual portions of the device. For example, U.S. Pat. No. 4,065,700 (Liebman) discloses a DC-powered strobe light circuit which employs oscillating means which are connected to the DC source and integral to the circuit. However, it would be advantageous to employ means for generating the oscillatory signal which are external to the circuitry associated with means for generating the visual signal, due to the greater power requirements and component costs of having the oscillatory signal generating means within the circuitry used to generate the visual signal. It is another object of this invention to employ an oscillatory signal for use in generating an audiovisual signal wherein the oscillatory signal is generated external to the portion of the device used for generating the visual signal.